In recent years, in order to manufacture tires capable of satisfying both of low-fuel consumption performance and fracture characteristics, intense study has been made on rubber compositions containing silica.
However, since the silica has poor dispersibility in the rubber compositions, the vulcanized rubber compositions tend to fail to exhibit sufficient rolling resistance performance, mechanical strength and abrasion resistance.
In addition, in order to attain good reinforcing properties by bonding the silica and rubber component with each other, a silane coupling agent such as sulfide silane is generally used in the rubber compositions. Even in such a case, owing to insufficient bond between the silica and rubber component, the resulting rubber compositions tend to have a low stiffness, i.e., are unsatisfactory in steering stability.
To solve the above conventional problems, in PTL1, as a rubber composition that can be improved in the aforementioned properties in a well-balanced manner, there has been proposed a rubber composition that includes a rubber component, silica and a silane coupling agent having a specific molecular structure at a predetermined compounding ratio.
Meanwhile, PTL2 and PTL3 describe a polymer of β-farnesene, but fail to have a sufficient study on practical applications thereof.